Opioids: formulations and properties

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Opioids: formulations and properties
Some preparations of opioids have immediate-release characteristics, others are available as modified-release formulations, and some are a combination of both.
Modified-release formulations should never be crushed or chewed, as this destroys their release properties and can result in a large dose being absorbed over a short period.
See Box 1.2 for advice about converting from immediate-release to modified-release morphine preparations.
A comparison of approximate equivalent doses of various opioids is shown in Table 1.4.
Table 1.3 below lists some opioid preparations and their properties. Awareness of the many available strengths and formulations is essential to avoid medication errors.
Properties of common opioid preparations available in Australia (Table 1.3) [NB1]
Opioid Active metabolite Dose adjustment in renal impairment Duration of action (hours) [NB2] Preparation
alfentanil
no
no
dose-related: 10 to 30 min for 1.5 to 3 mg/70 kg
injection
buprenorphine
no
no
6 to 8
sublingual tablets (Temgesic)
injection (Temgesic)
7 days
transdermal patch (Norspan Transdermal Patch)
codeine
yes
yes
3 to 4
linctus
 
tablet
dextropropoxyphene
yes
yes
6 to 12 (metabolite 30 to 36)
capsule
fentanyl
no
no
0.5 to 2
lozenge
injection
72
transdermal patch (Durogesic)
hydromorphone
probable minimal effect except in patients with renal impairment
yes
2 to 4
oral liquid
tablet
injection
methadone
no
note that duration of effect increases with chronic dosing
6 to 8 initially, then increases with chronic dosing up to greater than 24 hours
syrup
tablet
injection
morphine
yes
yes
2 to 3
injection (sulfate)
injection (tartrate)
immediate-release oral mixture
immediate-release tablet
24
modified-release capsule (MS Mono)
12
modified-release suspension (MS Contin)
modified-release tablet (MS Contin)
12 to 24
modified-release capsule (Kapanol)
oxycodone
yes
yes
3 to 4
oral liquid (OxyNorm Liquid)
immediate-release capsule (OxyNorm)
immediate-release tablet (Endone)
12
modified-release tablet with immediate-release component (OxyContin)
uncertain
suppository (Proladone)
4
injection (Oxynorm Injection)
pethidine
yes
yes
2 to 3
injection
remifentanil
no
no
dose related (biological half-life of 3 to 10 minutes)
injection
sufentanil
no
yes
dose-related (40 to 87 min)
injection
tramadol
yes
yes
3 to 6
immediate-release capsule
immediate-release oral drops
injection
12
modified-release tablet
NB1: only opioids discussed in these guidelines and preparations containing an opioid as the single active component are listed
NB2: approximate only

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